排序方式: 共有29条查询结果,搜索用时 15 毫秒
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探讨了测定四大怀药中微量元素铁和锌的新方法.用高压密闭微波消解-火焰原子吸收法测定四大怀药——怀山药、怀菊花、怀地黄、怀牛膝等怀药中微量元素Fe和Zn的含量.铁的回归方程为y=0.0968x+0.0114,r=0.9995(n=6),线性范围0-6.4μg/mL,平均回收率91.29%-101.06%,RSD为1.334%-4.314%.样品铁含量为159.091-1535.64μg/g.锌的回归方程为y=0.4207x+0.0039,r=0.9996(n=6),线性范围0-1.2μg/mL,平均回收率93.58%-100.85%,RSD为1.145%-3.634%.样品锌含量43.571-70.357μg/g.微波消解法消解样品,具有省时、简便、经济、消解完全、污染少等特点,可用于怀药微量元素的测定. 相似文献
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建立了UV-Vis分光光度测定红枣中多糖含量的方法.考察了乙醇体积、超声温度、超声时间、料液比4因素对多糖含量测定的影响.在单因素试验结果的基础上,进行正交试验设计,试验结果表明:最佳测定条件为A2B2C3D2,即超声温度为50℃,超声时间为60min,料液比为1∶30(g/mL),乙醇用量为30mL.方法平均回收率为96.87%,RSD为1.11%(n=5).该法快速、灵敏、准确,可用于红枣多糖的提取及含量测定. 相似文献
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A simple yet accurate interconnect parasitical capacitance model is presented. Based on this model a novel interconnect bus optimization methodology is proposed. Combining wire spacing with wire ordering, this methodology focuses on bus dynamic power optimization with consideration of bus performance requirements. The optimization methodology is verified under a 65 nm technology node and it shows that with 50% slack in the routing space, a 33.039% power saving can be provided by the proposed optimization methodology for an intermediate video bus compared to the 27.68% power saving provided by uniform spacing technology. The proposed methodology is especially suitable for computer-aided design of nanometer scale on-chip buses. 相似文献
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The problem investigated is the break of a high-pressure pipeline carrying natural single-phase gas which may condensate (retrograde) when the pressure drops. Single-phase non-ideal gas is assumed using a general- ized equation of state. Taking advantage of the choked massflow condition, the break is split into a pipe flow problem and a dispersion flow problem, both solved using a finite difference control volume scheme. The transient flow field from the pipeline break location is expanded analytically, using an approximation of the governing equations, until ambient pressure is reached and matched to the corresponding gas dispersion flow field using as subgrid model a jet box with a time-varying equivalent nozzle area as an internal boundary of the dispersion domain. The turbulence models used for the pipe and dispersion flow fields are an empirical model of Reichard and the k–ϵ model for buoyant flow respectively. The pipe flow simulations indicate that the flow from the pipeline might include dispersed condensate which will affect quantitatively the mass flow rate from the pipeline and qualitatively the gas dispersion if the condensate rains out. The transient dispersion simulation shows that an entrainment flow field develops and mixes supersaturated gas with ambient warmer air to an unsaturated mixture. Because of the inertia of the ambient air, it takes time to develop the entrainment flow field. As a consequence of this and the decay of the mass flow with time, the lower flammability limit of the gas–air mixture reaches its most remote downstream position relatively early in the simulation (about 15 s) and withdraws closer to the break location. 相似文献
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The reduced matrix elements of the component z i of the inter-electronic spin-other-orbit interaction have been calculated for all the states of the atomic f shell. Three of the z i , each of which belongs to the irreducible representation (30) of Racah's group G2, are found to exhibit matrix elements that are often related to one another in ways that go beyond what the Wigner-Eckart theorem, generalized to G2, would predict. Examples are presented for matrix elements whose bras belong to the IR (20) of G2 and whose kets belong to (31). The challenges to current theory are discussed. 相似文献
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DRAŽEN ADAMOVIĆ 《Transformation Groups》2016,21(2):299-327
We shall first present an explicit realization of the simple N = 4 superconformal vertex algebra L c N?=?4 with central charge c = ?9. This vertex superalgebra is realized inside of the bcβγ system and contains a subalgebra isomorphic to the simple affine vertex algebra L A1 \( \left(-\frac{3}{2}{\varLambda}_0\right) \). Then we construct a functor from the category of L c N?=?4 -modules with c = ?9 to the category of modules for the admissible affine vertex algebra L A1 \( \left(-\frac{3}{2}{\varLambda}_0\right) \). By using this construction we construct a family of weight and logarithmic modules for L c N?=?4 and L A1 \( \left(-\frac{3}{2}{\varLambda}_0\right) \). We also show that a coset subalgebra L A1 \( \left(-\frac{3}{2}{\varLambda}_0\right) \) is a logarithmic extension of the W(2; 3)-algebra with c = ?10. We discuss some generalizations of our construction based on the extension of affine vertex algebra L A1 (kΛ 0) such that k + 2 = 1/p and p is a positive integer. 相似文献
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